Gear-grinding machine



June 1 1926. 1,587,058

G. WIRRER GEAR GRINDING MACHINE Filed June 2l, 1923 8 Sheets-Sheet l lo ATTORI/Irs June 1 1926. A 1,587,058

G. WlRRr-:R

GEAR GRINDING MACHINE Filed June 21. 1923 8 sheets-smet 2 from/frs June 1 1926.

G. WIRRER- GEAR GRINDING MACHNE Filed June 2l, 1925 8 Sheets-Sheet 5 a, au

June 1 1926. 1,587,058

G. WIRRER GEAR GRINDING MACHINE Filed June 21, 1923 8 sheets-Shet 4 A TTHNEVS June 1 1926.r

G. WIRRER GEAR GRINDING MACHINE Filed June 21, 1923 8 Sheets-Sheet 5 .yyllII llluulvllln@ HHII qll

a Afro/mers June R926.

G. WlRRER GEAR GRINDING MACH Filed June 21, 1923 a 'sheets-Sh'ei e /n/l/EA/TOR QMW af@ M dw N70/mers June l 1926.

G. WIRRER GEAR GRINDING MACHINE Filed June 21, 1923 8 Sheets-Sheet '7 A TTOR/VEY `1,587,058 G. WIRRER GEAR GRINDING MACHINE Fild June 21, 1923 sheets-Shet s June 1 1926.

Patented dune l, i926.

GOTTFRIED WIRRER, OF PLAINFIELD, NEW JERSEY,

treinta MOTOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

enna-enrnmne MACHINE.

This invention relates to a machine for finishing gear teeth after cutting or heat treating and ,has for its principal object to generale an accurate prole of the gear teeth so that the gearswill runitrue and roll perfectly when in mesh. Heretofore, gear grinding machines as known haveV provided devices for automatically indeiiing the work at the end of predetermined lateral strokes of the work carrier and after the work has been moved to a point beyond the grinder element. Such a relation of parts requires a stroke ofgreater length than 1s -necessary for the grinding operation and entails an appreciable loss of time in the grinding. ln the improved machine movement of the work laterally is continued only so long as the grinder element is in operative relation to the work, the working strokes being of the shortest possible length and the indexing being done'by withdrawing the work directly away from the grinding element at the end of predetermined working strokes. By this relation of parts the grinding operation is carried on con? tinuously except during the indexing periods, the working stroke is shortened and the time ordinarily lost when the work is out of engagement with the grinder is eliminated. The result described is secured by mounting the work on a cross slide which is reciprocated laterally with respect to ther grinder element and by mounting this work carriage on a table which itself may be moved directly outward away from the grinder at predetermined intervals to carry the work outward away from the grinding element when indexing is to be effected.

Another object of the invention is to provide in such a gear grinding machine simple and eiiicient devices for carrying on harmoniously and in proper co-ordination, the respective movements of the workcarrying slide and the supportingr table whereby the indexing 'may be brought about automatically in proper relation to the movements of the parts. v

Still another object of the invention is to incorporate in such a machinemeans which are alsoro-ordinated with the above de scribed devices for raising and lowering the supporting table with its cross slide with a step by step movement at the end of predetermined working strokes so that, when necessary, gear teeth of broad faces or the teeth of a plurality of superimposed gears may be finished before the work is indexed for the grinding of other teeth, the effect being to draw the work across the grinder. nThese devices include generally a vertical slide on which the above described work tableand cross slide are mounted, a screw for raising and lowering the said vertical slide, and an intermittently operable ratchet for rotating the operating screw in proper relation to the other movements of the machine.

@ther features of the invention have to do with improved means for mounting r0- tary grinders adjustably on the frame of the machine and in such relation to one another and to the work as to function simultaneously and effectively for grinding different faces of the work, such as different faces of two teeth of a gear.

Still other features of the invention are concerned with details of construction which make all of the operating parts simple, accessible, rugged and invariable in operation.

The broad principles involved in the invention will be better understood with reference to the detail description of the preferred embodiment thereof illustrated in the accompanying drawings wherein: Figure l is a view in front elevation of the machine showing generally the relation between the vertical slide, the sliding table thereon, the work carriage slidable transversely of the table, the work support thereon, and the grinding elements.

lFigure 2 is a view in plan of the machine shown in Figure l.

Figure 3 is a view in side elevation thereof.

F igure't is a detailed view on a somewhat larger scale showing the mounting of the rotary grinding elements.

Figure 5 is a detailed view in side elevation of the mounting for the truing device for one of the grinders.

Figure 6 is a detailed view in side elevation of the actuating ratchet for turning the screw which moves the vertical slide.

Figure 7 is a view partly in horizontal section and partly in plan ofthe, elements 105 shown in Figure 6.

n Figure 8 is a view shown in Figure 6.

Figure 9 is a fragmentary view in elevation of one of the actuating pawls of the ratchet. 1

in plan of the parts ASSIGNOR TO INTERNATIONAL Figure is a view in plan showing particularly the devices for effecting movements of the work table periodically for carrying the work away from the grinder element for indexing.

Figure 11 is a fragmentary view partly in vertical section through the pitman and -`sliding abutment illustrated in Figure 1() for throwing the table out for indexing.

Figure 12 is a view in transverse section through some of the parts shown in Figure 11 for throwing out the table for indexing, while Figure 12l shows diagrammatically the relation of parts when the table is vthrown out. .j

Figure 13 is a fragmentary view partly in section and partly in elevation showing the supporting chuck for the work spindle and the bands for imparting a rolling movement thereto upon reciprocation of the wolk carriage.

Figure 14 is a transverse view in horizontal section through the chuck shown in Figure 13 and taken on the plane indicated by the line 14--14 of Figure 13 and looking in the direction of the arrows and indicating particularly the holding pawl which is automatically thrown out when the chuck is rotated for indexing.

Figure 15 is a view in vertical section through the parts shown in Figures 13 and 14 but taken on the plane indicated by the line 15--15 of Figure 13 and looking in the direction of the arrows.

Grinding Elements and T 'ming Devices. Before proceeding with the description of (the means for automatically presenting the work in proper relation to the grinding elements and for indexing it periodically a description of suitable grinding elements for finishing the work accurately and their mounting `on the frame of the machine and of suitable truing devices which are preferably mounted in operative relation to the grinding elements, will be given. The base a 'of the machine has mounted thereon vertical standards a', a2, to which are secured adjacent their upper ends a cross member b. The cross member Z carries on its front face a transverse way b on which is supported slidably brackets c, c', movable transversely by independent adjustable screws c2, c3, respectively, journaled on the vertical standards c', a?, and engaging the respective sliding brackets. On the brackets c, c', are mounted swiveled plates c4, fr", respectively, the angular positions of which may be adjusted by bolts c, c7, respectively, engaged with the respective brackets o, c, and passing through slots c3, 09, in the respective plates. On the angularly adjustable plates c4, o5, are mounted slides 01, c, respectively, which may be moved independently on their ways by hand-Wheels 012 carried on work screws c13 operatively engaged with the respective slides. On the slides 01, ou, aresecured journal bearingsI c14 in which are journaled supporting shafts c for the grinding wheels c1G which, by the construction described, are mounted in opposed relation as indicated clearly in Fi ure 4. Power for rotating the grinding wheels may be applied through pulleys c carried on their respective shafts. v

The form and construction of the grinding wheels c1G constitute no part of the present invention and grinding elements having other characteristics may be employed in i the machine Without departing from certain of the claims appended hereto. 1When the wheels are of the truncated conical form illustrated it may be convenient to associate. therewith a gauge element for facilitating their setting so that the grinding edge face will function in proper relation to the pressure line of the particular element being ground. To this end, there is mounted on the cross member Z) a bracket d which carries an adjustable slide d with which may be carried a positioning member Z2 having oppositely inclined side edges of proper angularity and movable into engagement with a tooth or teeth of the lg'ear to determine its initial setting in proper relation to the grinder wheels. With such a setting, for instance,- proper grinding is assured. For setting the grinding wheels with the proper angularity for grinding the gear teeth a loose gauge element d3 of the form indicated in dotted lines in Figure 4 may be placed on the positioning member ZZ when the latter is projected. The gauge element als may have beveled faces d4, d5, which form an included angle and against which the grinding edges ot the respective wheels rest flatly when the Wheels are properly set for the grinding of teeth having a predetermined pressure anigle.

It is proposed in the preferred form of the invention to mount on the bracket d and in proximity to the respective grinding Wheels c1G truing devices Which may be conveniently manipulated for truing either one of the Wheels as required. Such devices are shown as comprising rocking bell crank levers e pivoted respectively in swiveled supports e carried on the bracket d, one arm of each of the bell cranks being formed as an handle e2 and the other arm carrying a diamond point e3., The mounting is such that when either bell crank e is rocked the diamond point is moved in a plane parallel to the grinding face of the proximate Wheel 016.. The Wheel may have its grinding face drawn into engagement with the diamond when thus swung by moving the supporting slide 010 or 011 as the case may be. No matter how the cutting face is Worn, accordingly, it Will be trued oil' in the proper plane for continued grinding of the Work. The diamonds after this initial setting remained fixed and serve as gauge members against which the grinding wheels are drawn to determine ltheir proper position from time to time with reference to the work, thewheels being mov able against the diamonds. It is preferredI to have the axis of the cutting diamond disposed somewhat angularly to the cutting face to be trued so'that the diamond will be worn at one side when moved to and fro across the face. The support for ,each diamond in the arm of the bell crank' e is such that it may be rotated on its own axis from time to time to present an unworn portion for the next truing operation.

Support for the work and devices for mpartng desired movements `thereto.

(l0-operating with Ways a3 carried with the vertical standards a', a2, (Figure 10 )is a vertically reciprocable slide f which may be formed with a forwardly extending horizontal support f for the slides to be ldescribed. The vertical slide f may be counterba'lanced by weights connected thereto in any suitable manner y cords g passing over pulleys o* supported on the vertical standards e', a2, these standards, if desired,

being hollow, to receive the weights.

The horizontal section. f of the vertical slide f is formed with ways f2 at its opposite sides to co-operate with a slide h which is adapted to move in andout with respect to the grinding elements at predetermined times when the Work is to be indexed'. 'lhe slide h is formed on its upper surface with transverse ways 7L to receive the transversely reciprocable Work carriage i which slides transversely of the grinding element to present the work properly thereto for grinding.v

The work which is to be supported in operative relation to the grinding elements is illustrated in the drawings as a spur gear. Such work may be mounted on the work carriage in a hub i fixed to the slide 'i'. A s shown in Figures 13-15 the hiibz" may support a bushing 2 in which -is rotatably 'mounted hollow work spindle 3 Which may be changed as necessary to receive adapters of various sizes on which the work is carried. The hollow work spindle i has keyed to its lower end as ati* a gear 2' by which indexing is effected at predetermined -times in a manner to be described.

The slide z' is constantly reciprocated transversely of the grinding element, during operation of the machine by means of a pitman le illustrated as a forked rod pivoted to the slide as at lc and pivoted at 4its other end to acrank disk k2 by means of a crank pin carried on a slide las which is adjustable in the crank disk k2 along a diameter thereof whereby the radius on which the connecting crank pin rotates may be varied to change the amplitude of travel of the work slide z" as may be necessary. The crank disk k2 is supported on a. shaft 7a4 journaled in the Vertical slide f and connected through double universal joints 105, lr6, and a telescoping shaft section k7 with a driving rear les connected operatively with the main source of power.

Movements of the slide in and out with respect to the grinding element when indexing is to be eii'ected at predetermined times, is accomplished through a pitman Z pivot-ed at Z to the wor-k slide z' and at its other end to a slide m through a'pin m carried thereby, the slide m being reciprocably'mounted for movement in and out on a permanently adjustable slide n carried on the vertical slide f, which slide n is adjustable initially by means of a screw n having a hand-wheel a2 at the front of the machine for adjustment. .During the grinding operation, when the Work slide z' is reciprocated transversely by the pitman le the supporting slide L will have no tendency to move in and out. The arm Z will swing back and forth and the slide m may be reciprocated in and out on ithe slide n las the pin Z travels in a straight In connection with the indexing operation the conventional means for causing the work to oscillate on its spindle when moved back and forth with relation to the grinding element should be understood. The slide z. has depending arms h2 at opposite sides thereof to which are secured adjustably the free ends of Bilgram bands o, o', the inner ends of which are fastened at opposite sides to the periphery of a drump. This drum is secured to a hollow shaft g which carries a radially extending arm g in which is slidably mounted a spring-pressed pawl g2 for the purpose which will later appear. The pawl q2 under the influence of a spring gs normally engages the indexing gear i5 4skilled in the art. l

It is proposed in accordance with the present invention to Alimit the transverse reciprocations of the work slide c' to the extent necessary to insure uninterrupted grinding during each work stroke with` no additional lost motion. this stroke, as has'been pointed out -hereinbefore, is determined by the adjustmentl The amplitude ofv been the common practice in grinding opera tions to reciprocate the work table a sullicient distance each stroke to carry the Work wholly out of engagement with the grinding element and then, eect the indexing while f the work is beyond the grinding element. This involves considerable loss of time. By the present invention it is proposed to move the slide z. away from the grinding element at predeterniined times for indexing. Such amovement of the slide will, of course, carry with it the work slide z' which is mounted on it and the work. In order to force the slide /1y outwardly in this manner suitable means are indicated in Figures 1042. In the slide 1t is mounted a transverse locking slide n10 which preferably has a spring n back of it tending always to force the slide in rear of the slide 111. so as to hold the latter against reciprocation. However, the slide f1.1" is normally held out of the path of the slide 111l by means ofa slide 11,30 which is normally forced in the opposite direction by means of a spring 11.4. A slot and pin connection may be interposed between the slide 113 and the throw out slide 11.10 so that when the slide 11.3 is projected the slide 111 will be out of the path of the slide 111l and yet the slide 113 may move inwardly relatively to the slide 111, thereby compressing the spring 11,20 before the ,slide 111 snaps in behind the slide 111. which may occur when the latter is in its forward position. On the inner face `of the standard a2 may be mounted adjustably a stop a5 which is engaged periodically by a roller 11.50 mounted on the end of thel slide n30. As will be'described later, vertical step by step reciprocations may be given to the slide f for the purpose of carrying the grinding elements over the entire surface which is-to be ground and it is at the end of certain of these step by step movements that thelroller 11.50 will run onto the stop a5 so as tof move the slide n30 inwardly and place the spring n2 under compression. With the parts in such position, at the end of one of the transverse reciprocations of the work slide 11, the connecting arm Z will draw the slide m forwardly to a position where the locking slide n10 may snap1in behind it. During the next reciprocation' of the sliding work table 11 the slide m will be held against rearward movement thereby fixing the pin 111/ relatively and, when the arm Z starts to swing, forcing the slide 71. outwardly and with it, of course, the slide 11 which is carried thereby and the work. In this manner, the work is carried out of engagement with the grinders. IVith the parts in this relation the indexing is effected, vthat isto say, the angular position of the work spindle 123 is permanently changed so as to bring other parts of the work, such as other gear teeth, into position for grinding. -To accomplish this inthe most convenient manner it is desirable to disconnect the pawl g2 from the gear 5 momentarily without interfering with the action of the Bilgram bands on the drum p so that the arm g will continue to swing and when the pawl g2 is re-engaged with the gear 5 it will engage another tooth thereof. The work slide z' carries a bracket 1' which is supported on two rods 1- journaled, in the work slide and free with respect thereto so that the slide may' move in and out during indexing without hindrance. The rear ends of the rods 1 are connected by means of a T-head 12 engaged by a slide 1'-3 fixed through a distance rod 14 to the slide 11. (Figures 1045). On the bracket 1' is supported a cam s carried on a pivoted arm s journaled on a pin s2 which is engaged operatively by a suitable spring s3 to hold the cam yieldingly in desired relation to a roller g4 on the pawl q2 for co-operation in a manner which will later appear.

On the bracket 1 is also pivotally mounted a brake arm t pivoted at t and normally held in retracted position by a spring t2 to maintain the braking element t3 out of engagement with thev teeth of the indexing gear 5. The braking element 153 may be moved yieldingly into engagement with the teeth by\ means -of a pivoted follow-er t* which is backed by a spring follower 155.

The free end of the brake lever t is also 'disposed with respect tothe path of the tions of the work table during grinding op- I erations will carry the roller g4 to and fro back of the cam s. When, however, the locking slide 11.1 snaps in behind the slide 1n; in the manner hereinbefore described the pitman Z will swing about a fixed center and during the next lateral reciprocation of the work slide z' cause this slide with the work to be carried outwardly away from the grinding element. This outward travel combined with the transverse movements will carry the roller g* along the face of the cam s so that the pawl Q3 is withdrawn for engagement from the indexing ear' 115. I proper timed relation to that action, the ro 1er g4 presses against the brake arm t so as to throw the brake element t3 yieldingly against the gear teeth of the indexing gear so that it will be snapped into engagement with one ofthe teeth by the action of the follower spring t5 when in alignment with one of the teeth. The indexing gear g. On the reverse stroke with the pitman still swinging about its fixed center the workl slide z' will be slowly retractedv as the radius shortens Accordingly, thel roller g4 will run against the arm s which carries the cam s and this arm will yield angularly on its pivot pinagainst the action of the spring s3 and be restored to normal operating position against its abutment after the roller g4 has been thrown wholly out of engagement with it. At the end of this said reverse stroke the work slide i will end up in position to start the next succeeding work stroke and at that instant the locking slide n10 will be movedvout of engagement with the slide m under the inluence of the predominant spring 11,40, as described. Subsequent recprocations of the work slide will carry that portion of the work then presented` for grinding in proper relation to the grinding elements. The path of travel of the work slide during indexing and during normal grinding operations is indicated diagrammatically by the views shown inFigure 12a.

Vert/cal feed re/vices:

Improved devices .are provided for imparting a step by step vertical movement to the slide f either upwardly r i downwardly, as required, and these devices are c aracterized by compactness, simplicity, accessibility and the positive nature of their actuation of the slide. VGenerally speaking, they comprise a ratchet wheel which is driven by one of two pawls adapted to be reciprocated through connecting rods, respectively, pivoted to a rotating crank disk, the pawls being thrown into and out of operative engagement with the ratchet wheel automatically by stops which are susceptible of adjustment to insure this engagement, at predetermined times with respect to each `of the pawls so that not only will the slide be moved in the desired direction but will be moved in that direction during predetermined periods. Referring particularly lto Figures 6-9 is appears that a rotating disk u which may -receive its movement through a sprocket u engaged by a chain u2 (Figure 3) driven from the main power shaft us, has pivotally connected thereto as at M4 two connecting rods @e2/u", which are pivotally connected to opposed oscillating` arms a7, u8, respectively, at opposite sides of their axis of oscillation. These arms to?, u8, have extended concentric hubs u?, um, respectively, which are journaled on a hollow hub e of a ratchet disk 'u'. On the arms a7, u8, are pivoted pawls u, M12,

respectively, the noses of which are adapted to co-operate with the ratchet disk 'v' and the tails of which are formed with notches u for engagement by spring-pressed detents u carried in theends of the arms u?, u8, and adapted to maintain the pawls yieldingly in any one of three positions for the purpose which will appear later. Each pawl u, 11,12, has an extended bearing hub one of which 'uw is shown in Figure 8 and with the hub is formed a depending finger u for co-operation with stops whereby the respective pawls are moved automatically into and out of engagement with the ratchet disk fu". The hub v of the ratchet disk 'v' is keyed to a shaft w which has an extended section w of reduced diameter on which is mounted loosely the hub of a separate disk m', the periphery 'of which is formed lwith a circumferential undercut slot to reit of the vertical slide f. The stop disk has an open face and an internal gear m4 cut on 'its inner periphery for engage` ment by planetary pinions y which rest within the open face and are journaled on short shafts y, respectively, bolted throu h a disk y2 having aniextended hub ya loose y mounted on an extended hub e of a pinion e which is also engaged by said pinions.

rlhe hub .e is keyed to the shaft section w of reduced diameter so that rotation of the shaft imparts a rotative movement to the stop disk through the planetary gearing described but at considerable reduction to the end that the stop disk shall rotate at considerably less speed butin predetermined timed relation to the ratchet disk 'v'. The shaft section w which is keyed to the ratchet disk 'u'` and is rotated by the direct action of the ratchet disk may be journaled as at L02 in the frame a of the machine and carry a spur gear w8 which is meshed with the pinion wt on a shaft fw? .which is arranged to drive the vertically disposed lift'screw rw for the vertical slide f, as through further reduction bevel gears fw?, w8.

In the operation of the vertical feed de? vices above described itis to be remembered that the disk u has continuous unidirectional rotary movement and thereby effects continuous reciprocation of the connecting Ill() Y ments of the machine.

rods u, as and continuous oscillation of the pawls u, 1J/12. The respective stops r3 for the pawls co-operate with their lingers u at such times as to engage one of the pawls with the ratchet wheel while throwing the other pawl out of engagement therewith, depending upon direction of movement of the slide f desired. When once engaged the spring-pressed detents u will hold the pawls in the positions into which they are positively thrown by the stops and lingers and their condition will remain unchanged until such time as other appropriate stops are brought into engagement with said fingers through the slow rotary movement of the stop disk w to change the condition, as by disengagingv one pawl and throwing in the other. The effect of such a reversal necessarily effects a reversal in the direction of travel of the slide f as is desirable in accordance with the method of grinding employed. The action is positive at all times. VIt is certain in that the pawls pick up the ratchet disk quickly for actuation of the slide in exact predetermined timed relation to the other move- The driving mechanism is self-contained in a more or less unitary sense, the parts thereof are accessible and the desired timing may be accurately determined by manual adjustment of the stops-in the stop disk Aside from the automatic operation obtainable by these devices they lend themselves lto manual actuation of the vertical slide' f as through application of a wrench or other suitable tool to the extended hub e which may be of irregular external cross section. When any such manual operation is to be effected it is desirable to throw the pawls un, um away from the ratchet disk o to a point beyond where their fingers may be engaged by the stops ma, one of the notches u in the tails of the pawls making it possible to retain them in this remote position through the detents w14.

The principle involved inthe grinding .has been described fully hereinbefore and it is to be understood that the invention in a broad sense is concerned primarily with devices which lend themselves to the practice of grinding in accordance with this principle rather than in thedetails of con'- struction of the parts illustrated in the accompanying drawings. It will be evident to one skilled in the art, for instance, that other mechanical movements than those described may give, with some degree of commercial operationl satisfactoryA results although differing in form and arrangement from the illustrated embodiment. Any departures in matters of design and arrangement of elements are to be deemed 'within the spirit fof the invention so long as the results described :are secured by means upon transverse movements of the slide,

means to arrest movement of the slide at a point when the workis about to leave the grinding elementv and means to move the work laterally away from the grinding element to disengage the work from the grinding element for indexing during predetermined strokes.

2. In a gear grinding machine in combination with the frame thereof, a Work supporting table carried with the frame and means to move the work table away from the grinding element, said means including a connecting rod connected with the table, a slide pivoted to the connecting rod and movable freely, means tol lock said slide periodically to fix one end of the said connecting rod, and means to swing the connecting rod about said -xed end as a center.

3. In a gear grinding machine, vin combinatio-n with the frame and grinding element, a work carrying slide, means to reciprocate the slide laterally with respect to the work, a work carrying table on which the slide is mounted, a connecting rod pivoted to the slide, a locking slide pivoted to the free end ofthe connecting rod and normally reciproca'ble freely upon lateral reciprocations of the work carrying slide and means to lhold said locking slide against such ,reciprocations during predetermined strokes of the work carrying slide.

- 4. In a gear grinding machine, in combination with the framel and grinding element, a work carrying slide, means to reciprocate the slide laterally with respect to the worka work carrying table on which the slide is mounted,` a connecting rod pivoted to the slide, a' locking slide pivoted to the free end of the connecting rod and normally reciprocable freely upon lateral reciprocations of the work carrying slide and means to hold said locking slide against such reciprocations during predetermined strokes of the work carrying slide, such means including spring-loaded plungers movable into position behind said locking slide and meanscarried with the frame to force such' springloaded plungers into such position.

5. In a gear grinding machine in com- A bination with the frame and grinding element, a work carrying table movable vertically with respect to said frame power means tomove said table automatically at predetermined times. and weights to cbunterbalrying slide laterally away from to the grinding element for indexing and means operable in predetermined relation to said later-v al reciprocatio-ns of the work carrying slide to move the vertical slide.

7. In combination with a driving shaft and a driven shaft transmission devices adapted to transmit uni-directional rotation of the drive shaft to the driven shaft to rotate it in different-directions for predetermined periods of time including a revolving crank pin carried with the power shaft, connecting rods pivoted to the pin, arms journaled on the driven shaft, means to connect the said connecting rods pivotally to the respective arms at opposite sides of the driven shaft, pawls 'pivoted on said arms, a ratchet wheel keyed to the driven shaft and adapted to be engaged operatively by one or the other of said pawls and means to throw the said pawls into and out of engagement with said ratchet wheel automatically at predetermined times.

8. In a machine of the character described in combination with a uni-directional rotating driving shaft, a revolving crank pin carried therewith, connecting rods pivoted tothe crank pin, a driven shaft, means to automatically drive the driven shaft from the driving shaft in different directions during predetermined periods, and including pawls supported operatively on the driven shaft at opposi-te sides thereof, means to pivot the connecting rods operatively ywith the respective pawls, a ratchet wheel connected with the driven shaft and adapted i to be engaged operatively by one or the other of said pawls for rotating the shaft in one direction or the other, a rotating tripping element mounted loosely on the driven shaft in proximity to the said ratchet wheel and having stops adapted to engage the pawls periodically and planetary gearing interposed between the driven shaft and the rotating tripping element whereby the latter is driven at a predetermined speed ratio to the ratchet wheel.

9. In a gear grinding machine in combination with a frame and grinder element, a slide movable vertically `von the frame to carry the work across the grinding element, and 'means to impart a step by step movement upwardly yand downwardly` to said slide, said means including a hoisting screw, a driving shaft, and means interposed operatively between the hoisting screw and the driving /shaft to impart rotary movement to the screw in tirst one direction and then the other at predetermined times. l

10. In a gear grinding machine in combination with a grinder element. a work carrying slide adapted for reci rocation laterally away from to the grining element for indexing, a spindle-on the slide to carry the gear, opposedbands to impart a rolling movement to the gear during lateral reciprocations of the slide, an operative connection between the spindle and the bands, and means apart from said operative connection to interrupt said connection periodically for indexing.

1l. In a gear grinding machine in combination with the frame and grinding ele-V ment, a slide to carry the work laterally away from the grinding element for indexing, a spindle on the slide, a gear carried with the spindle, a drum carried with the slide,opposed bands connected to the drums to impart a rolling movement thereto upon said reciprocations of the slide, .a pawl carried with the vdrum and engaged with the gear on the spindle, and means apart from the drum and associated mechanism to withdraw the pawl from the gear periodically for indexing. Y

12. In a grinding machine, in combination with va grinder element and work spindle, a work carrying slide adapted for reciprocation-transversely 'with respect to the grinding element., a frame supported on the slide, means to move the slide laterally away from the grinder element andmeansmounted on the frame to hold the work spindle against movement during such movement of the slide. 1

13. In a grinding machine, in combination with a `grinder element, a work carrying slide adapted for reciprocation laterally with respect to the grinding element, means to impart a rolling movement to the gear during such reciprocations of the slide including an oscillating pawl engaged with the gear support, a camsupportednormally out of the path of said oscillating pawl, and

means to move the slide with respect to the cam and away from the grinder element to bring the'pa'wl into loperative relation to the cam at predetermined times for momentary disengagement ofthe pawl from the gear support.

14. In a grinding machine, in combination with a grinder element, a. work carrying slide adapted for reciprocation laterally with respect to the grinding element, means toimpart a rolling movement to the gearduring such reciprocations of the slide including an oscillating pawlengaged with the gear support, a cam supported normally out o the lpath of said oscillating pawl, means to move the slide with respect Ato the cam and away from the grinder element to bring the pawl into operative relation to the 'Cam at predetermined timesv for momentary vdisengagement vot the pawl from the gear support,l and means supported Withzthe cam tohold 'the' gear support against movement during disengagement of the paWl therefrom. K

15.'In a gear grinding machine, in combination with a grinder element, a Work carryingl slide ladapted for reoiprocation .laterally with. respect to the grinding element, a spindle on the 4slide to carry' thiJ gear, a geary carried with the spindle, an

oscillating pawl' engaged With vthe last xnamed gear, opposed loandsv to impartV an 15 oscillating movement to ythe pawl, a frame carried' Withtheslide', a oam supported on the frame, means to move the slideaway -from the grinder element at predetermined 'times to bring the pawl into engagement `With the cam for momentary disengagement of the paWl from the second named gear, :and a brake' elementsupported on the said -frame .and engageable withV the said second -named "gear upon disengagement :of the paWl therefrom, and under the influence of the said oscillating arm. Y

This specificationA vsigned this 18th day of une A. D. 1923.

GOTTFRIED WIRRER.

feo 

